1. Field
The present disclosure relates to a semiconductor die that includes an integrated electro-static discharge (ESD) device to protect the semiconductor die from transient ESD signals.
2. Related Art
ESD events commonly arise during the manufacture, assembly or use of systems containing integrated circuits. While the amount of energy dissipated during an ESD event may be comparatively small on a human scale (akin to the shock you receive when touching a metal object after walking across a thick carpet), from the perspective of the small, sensitive electronics on an integrated circuit, the destructive power can be comparable to a lightning strike, and can cause significant damage to integrated circuits.
A variety of existing ESD-protection circuits and techniques are used to protect integrated circuits from ESD events. For example, one existing ESD-protection circuit includes reverse-biased metal-oxide-semiconductor (MOS) or PN diodes that turn on during an ESD event. However, when sized to safely absorb an ESD event, this ESD-protection circuit can significantly increase the parasitic capacitance of the input/output (I/O) pads in an integrated circuit. This increase in parasitic capacitance is problematic because it can: reduce edge rates by introducing inter-symbol-interference (ISI); cause reflections; and cause near-end or far-end crosstalk. These problems can significantly reduce the maximum data rate that can be communicated through I/O channels. Furthermore, parasitic capacitance consumes power as signals charge and discharge the additional load.
Additionally, the parasitic capacitance introduced by existing ESD-protection circuits (such as MOS transistors, PN junctions, or N-well resistors) is typically a nonlinear function of the transient ESD signal amplitude. This nonlinearity further deteriorates the I/O pad's termination properties for high-speed signaling, and introduces distortion in analog-to-digital (A2D) converters that limits their conversion accuracy.
Hence, what is needed is an ESD-protection circuit without the problems described above.